1. Field of the Invention
The present invention relates to medical apparatus and methods for convulsive therapy (CT), namely, electroconvulsive therapy (ECT) and magnetoconvulsive therapy (MCT), and methods for automatic measurements of electroencephalographic, electrocardiographic, and/or electromyographic events that occur during treatment with CT.
2. Description of the Related Art
In ECT generally two electrodes are applied to the head of the patient, one over the right temple and the other in a second location that is commonly either by the vertex of the head or over the left temple. A small amount of electricity in a selected wave or pulse form is applied through these electrodes. The aim of the application of this electricity is to cause a generalized centrencephalic seizure, also called a grand mal seizure. Such a seizure has therapeutic value for several mental illnesses, including depression, mania and schizophrenia (Abrams, 1992). A report of a panel of the National Institute of Mental Health in Science (Jun. 28, 1985, pp. 1510-1511) concluded that "not a single controlled study has shown another form of treatment to be superior to ECT in the short-term management of severe depressions."
Alternatively, the generalized centrencephalic seizure (grand mal seizure) may be induced by a pulsed magnetic field from a magnetic coil positioned proximate the patient's head. This procedure, called magnetoconvulsive therapy (MCT), is described in U.S. patent application Ser. No. 08/231,307 (allowed) to Abrams and Swartz, incorporated by reference herein. The description which follows generally employs examples of electroconvulsive therapy (ECT), since it is widely used and has been extensively researched. However, the methods and systems of the present invention are equally applicable to magnetoconvulsive therapy (MCV). The term "convulsive therapy" (CV), as used herein, includes both ECT and MCT as well as chemically induced convulsive therapy.
In ECT the physician-operator determines the dose of the electrical charge for the stimulus, which is the duration of the applied current. This is determined on the basis of the patient's age, sex, concurrent medications, and response to previous sessions of ECT. The physician may, with currently available apparatus, select an electrical dose likely to provide therapeutic value. These would be in the range of 0.25 to 1.5 millisecond pulse width of fixed current within the range of 0.8 to 1.0 amperes given at a rate of 40 to 140 pulses per second over a period of 0.1 to 11 seconds. For example, selection of the "Thymatron DG" instrument (TM of Somatics, Inc., Lake Bluff, Ill.) can provide a series of brief electrical pulses of 0.9 amperes and 0.5 millisecond pulse width given at a rate of 140 pulses per second for a period that is adjustable by the physician, from 0.4 to 8.0 seconds.
CT seizures differ in their intensity, nature and therapeutic value, and it is of importance to assure effectiveness in treatment by the measurement and description of bodily phenomena that are associated with the therapeutic value. The generalized centrencephalic seizure is accompanied by a variety of measurable physiological effects in the body. These physiological effects include generation of patterns of electrical activity by the brain (electrical brain waves) which are measurable on the head with an electroencephalograph (EEG), acceleration of the heart rate which is measurable on the chest with an electrocardiograph (ECG), and contractions of skeletal muscles which are measurable with an electromyograph (EMG). Measurable effects on the EEG, ECG and EMG can occur not only during the seizure, but usually on the EEG and ECG for several minutes afterwards, and sometimes on the EEG for several weeks afterwards. The form and intensity of the physiological effects presumably reflect the nature, intensity and therapeutic value of the CT seizure. Several studies have described relationships between physiological measurements and therapeutic value of the CT seizure. In addition, several logical considerations indicate several strong expectations of such relationships, most particularly that physiological signs of greater intensity, or extent, correspond to CT seizure of greater intensity or extent, which is of greater therapeutic benefit.
Several aspects of the EEG that are of interest to the operator cannot be judged by sight impression and must be measured, but are difficult to measure with a conventional EEG paper recorder, because of large time needs, tedium, imprecision and complexity. It is not part of the training of doctors to be trained to deal with data processing, and few doctors are knowledgeable about these subjects. Accordingly, present practices by doctors do not include such measurements; rather, doctors either do not attempt to judge the therapeutic value of the CT seizure or they do so only through the occurrence of a seizure of ordinary length, or by rough impressions about the shape of the EEG, as shown on a graph made by a paper recorder (Nobler et al 1993).
The inventors' prior U.S. Pat. Nos. 4,878,498; 4,873,891 and 4,870,969 are directed to monitoring the patient in ECT and these patents are incorporated by reference herein. U.S. Pat. No. 5,269,302 discloses various systems using EEG, EMG and ECG and provides indications of the termination of seizure.